Surfactant-aided exfoliation of molydenum disulphide for ultrafast pulse generation through edge-state saturable absorption

Howe, RCT and Woodward, RI and Hu, G and Yang, Z and Kelleher, EJR and Hasan, T (2016) Surfactant-aided exfoliation of molydenum disulphide for ultrafast pulse generation through edge-state saturable absorption. PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 253. pp. 911-917. ISSN 0370-1972 (Unpublished)

Abstract

We use liquid phase exfoliation to produce dispersions of molybdenum disulphide (MoS2) nanoflakes in aqueous surfactant solutions. The chemical structures of the bile salt surfactants play a crucial role in the exfoliation and stabilization of MoS2. The resultant MoS2 dispersions are heavily enriched in single and few (<6) layer flakes with large edge to surface area ratio. We use the dispersions to fabricate free-standing polymer composite wide-band saturable absorbers to develop mode-locked and Q- switched fibre lasers, tunable from 1535-1565 and 1030-1070 nm, respectively. We attribute this sub-bandgap optical absorption and its nonlinear saturation behaviour to edge-mediated states introduced within the material band-gap of the exfoliated MoS2 nanoflakes.